MMD models imported into blender are missing all textures?
This is an issue unique to MMD models in Blender due to the way MikuMikuDance understands shading, textures, and all things of that sort.
When you open an MMD model in Blender, you might see something like this.

(All of the following images are taken using the Blender 2.8 version of MMD tools)
There are several things we can try to get our textures looking normal and not so pink.
1. Disable Sphere Textures in the MMD Display tab.
Open your Visibility Sidebar on the right (usually can be opened by pressing N ) and navigate to the tab titled Misc. Under the section MMD Display, uncheck the box next to Sphere Texture.

If this does not correct any or only a few of your textures, continue to the next step.
2. Disable Toon Textures in the MMD Display tab.
Directly to the left of the Sphere Texture option from the last step, there should be an option titled *Toon Texture. Uncheck the box next to this option.

If this does not correct any or only a few of your textures, continue to the next step.
3. Turn off Use Shared Toon Texture.
Selecting the mesh of your model, navigate to the Material Properties tab under the Properties panel. You should see a list of all the textures being used on your model.

Select a texture you see on the list that has the pink hue we're trying to get rid of. For example, these textures are supposed to be a pale yellow but they are appearing as a vibrant pink in my textures list.

Once you have selected the texture, scroll down in the settings underneath the texture list until you find a section titled MMD Texture. There should be an option titled Use Shared Toon Texture in this section. Uncheck this option and see if the texture has gone back to normal.

If there is a part of your model that is bright purple still, there may be an issue with the model or a missing texture.
After trying these steps, your model should be back to normal. Mine turned back to normal once I unchecked Toon Textures in Step 2.

Something Important To Know
Some models rely on things like Toon Texture and Sphere Texture if they have a special shader attached to them (to make them look more anime-like, or because of the material the textures on it are trying to emulate).  If you have a model that only has a few sections turning up pink try Step 3 first on those textures in order to have the model work correctly. However, this method can also be used if you don't want those shaders on your model!